How to Choose the Right Amplifier For Your Sound System - The Basics
- Determine the needs of your system (Stereo, Home Theatre/Cinema, Desktop or Multi-Zone/Room)
- Look at the environment the system will be in (small apartment, large living room, office, outdoor)
- Decide what volume levels you want
- Ensure amp offers all the right inputs and features required
Determine Your Needs and Type of Environment Your System Will Be In
Let’s break it down to basics: first of all let’s determine the type of amplifier we are looking for, as someone looking for an amp for a pair of speakers to connect a laptop will have vastly different requirements to someone who is looking at a home theatre amp. The first key is to determine what you want from your amp: are you listening to music only or are you in to movies and gaming? Is this a desktop system or for a large room? If you are listening to music or only planning on using two speakers then a stereo amp is going to be the best bet. After that you will need to address the power issue which is determined by three factors – the sensitivity of your speakers, the size of the room and your required volume level. Whilst a small 15 watt amp would be great for a desktop or near-field monitoring it’s unlikely you will be happy with it in a large room, especially if you want to hear it loud.
Wattage is generally a misunderstood term. Don’t expect to hear a dramatic difference between say, a 100 watt amp and 200 watt amp as there will be little gains in actual SPL. In measured terms about 3 dB actually, which is noticeable but not dramatic. In any case amp manufacturers can “enhance” their specs by the way they measure them so approach this with caution. The other problem with wattage measurements is that there are contributing factors – the frequency the amp is measured at, the distortion and impedance, wether it’s measured with results from one channel or all channels - these can all affect the end result. To get a decent idea, a true measurement should be from 20 Hz to 20 KHz, at low distortion (less than .1% THD) all channels driven, and at 8 Ohms. At least when talking about solid state amps… valves are another matter. Also consider the sensitivity of the speakers as low sensitivity speakers will require more power to achieve the same volume level.
Power Amp or No Power Amp?
There are times when a surround receiver just won’t do it, so don’t be afraid to look at a power amp to drive your speakers. The advantages here are many but importantly you will get better performance and be spending your money on an area of the system that will be constant. Your speakers and amp will likely last for many years, but there is a good chance there will be other desirable features, standards or processing for your receiver (look at the change in HDMI standards and 3d).
What Inputs Do You Need?
So now we know what type of amp (mini, stereo, home theatre) and we have a rough idea about power output, so what next?
If it’s stereo you want to ensure that the inputs are there. No point getting an amp that won’t accept all your sources. Of course if you don’t want an outboard phono stage for your turntable then you need to make sure the phono stage is there and it appropriate for the cartridge you have.
If it’s a HT amp you will have more to consider when it comes to features: do you want to stream music, have internet radio, multiple zones all controlled independently? They all have a bunch of HDMI inputs but what if you run a projector and a conventional flat screen? If you want to use a power amp later on you will need to make sure the receiver had pre-outs too. If you have a HT system and still listen to music then being able to select “pure direct” will be an advantage as it bypasses all superfluous features to give you better sound, even switching off the display and video switching. How about multi-channel stereo? (Great for parties if you just want to fill the room with music) And I haven’t even covered video switching or upscaling. There is a huge array of features so choose the right mix carefully but don’t get bogged down in it. If you didn’t know it existed before you probably didn’t need it.
This also brings me to the last (and in my opinion the most important) issue: sound quality. Personally I would dump all the features in favour of an amp that sounds good, so remember what you are doing with the amp – amplifying! Sounds obvious but its often overlooked. Audition the amp with the speakers you are planning on buying as this is the only way you will get an indication of how it will actually sound. It’s important that the sales person will allow you to listen to a few combinations as you do need a point of reference, so make sure they are willing to help you out. Your specialist is the best person to assist here, and remember that it’s your opinion that counts. It’s your ears - and your wallet - so chose what youlike the sound of!
Potential Krix System Configurations
Atomix and a T-Class Amplifier. There are some great little t-class amps that will do the job and some offer internal DAC’s. The desktop system I have is awesome although the amp maybe overkill for some. (image above)
Starter – Equinox and Integrated Amp (small apartment style living room)
Purist – Neuphonix and Pre-Amp + Power Amp (bigger living and listening area)
Starter – Rhythmix Collection and AV Receiver
A Few Notes From Andrew in our Research and Development Department
When trying to achieve high SPL (Sound Pressure Level), larger more sensitive loudspeakers will generally always out perform smaller loudspeakers for a given amplifier power rating.
Low power stereo amplifiers often have better distortion performance than high power amplifiers, and these units should not be ruled out on the basis of power rating alone. Consider this with regard to the previous point.
Consider adding a separate high quality active subwoofer to lessen the demand on the main amplifier and loudspeakers if loud playback of bass heavy material is desired.
Where published the 10kHz Total Harmonic Distortion (THD) figure is a much better guide to amplifier’s performance than the same figure as measured at 1kHz.
Total Harmonic Distortion figures are only a small snap shot of the amplifier’s performance.
The harmonic distortion spectrum graphs, as published in a detailed product reviews, provides a much clearer overall picture of amplifier performance.
The size and weight of an amplifier is important with respect to it’s thermal performance, if continuous usage at or close to full power is expected. Also the presence of any thermally cued force air cooling fans and the noise created, that may otherwise distract from the listening experience or not depending on the listening level and the location of the amp.
Part 2 of the Amplifier Blog Series to be continued...
If you have any questions or feedback, or some of your own tips we would like to hear from you.